<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
  <script>
       var arr=[1,2,3,4,5,6];
      var  arr1 = arr.slice();
     arr.length=0;
       console.log(arr1)
       console.log(arr)
  </script>
</body>
</html>